ONCE you become accustomed to gas at $4 a gallon, brace yourself for the next shocking retail threshold: bananas reaching $1 a pound. At that price, Americans may stop thinking of bananas as a cheap staple, and then a strategy that has served the big banana companies for more than a century — enabling them to turn an exotic, tropical fruit into an everyday favorite — will begin to unravel.

The immediate reasons for the price increase are the rising cost of oil and reduced supply caused by floods in Ecuador, the world’s biggest banana exporter. But something larger is going on that will affect prices for years to come.

That bananas have long been the cheapest fruit at the grocery store is astonishing. They’re grown thousands of miles away, they must be transported in cooled containers and even then they survive no more than two weeks after they’re cut off the tree. Apples, in contrast, are typically grown within a few hundred miles of the store and keep for months in a basket out in the garage. Yet apples traditionally have cost at least twice as much per pound as bananas.

Americans eat as many bananas as apples and oranges combined, which is especially amazing when you consider that not so long ago, bananas were virtually unknown here. They became a staple only after the men who in the late 19th century founded the United Fruit Company (today’s Chiquita) figured out how to get bananas to American tables quickly — by clearing rainforest in Latin America, building railroads and communication networks and inventing refrigeration techniques to control ripening. The banana barons also marketed their product in ways that had never occurred to farmers or grocers before, by offering discount coupons, writing jingles and placing bananas in schoolbooks and on picture postcards. They even hired doctors to convince mothers that bananas were good for children.

Once bananas had become widely popular, the companies kept costs low by exercising iron-fisted control over the Latin American countries where the fruit was grown. Workers could not be allowed such basic rights as health care, decent wages or the right to congregate. (In 1929, Colombian troops shot down banana workers and their families who were gathered in a town square after church.) Governments could not be anything but utterly pliable. Over and over, banana companies, aided by the American military, intervened whenever there was a chance that any “banana republic” might end its cooperation. (In 1954, United Fruit helped arrange the overthrow of the democratically elected government of Guatemala.) Labor is still cheap in these countries, and growers still resort to heavy-handed tactics.

The final piece of the banana pricing equation is genetics. Unlike apple and orange growers, banana importers sell only a single variety of their fruit, the Cavendish. There are more than 1,000 varieties of bananas — most of them in Africa and Asia — but except for an occasional exotic, the Cavendish is the only banana we see in our markets. It is the only kind that is shipped and eaten everywhere from Beijing to Berlin, Moscow to Minneapolis.

By sticking to this single variety, the banana industry ensures that all the bananas in a shipment ripen at the same rate, creating huge economies of scale. The Cavendish is the fruit equivalent of a fast-food hamburger: efficient to produce, uniform in quality and universally affordable.

But there’s a difference between a banana and a Big Mac: The banana is a living organism. It can get sick, and since bananas all come from the same gene pool, a virulent enough malady could wipe out the world’s commercial banana crop in a matter of years.

This has happened before. Our great-grandparents grew up eating not the Cavendish but the Gros Michel banana, a variety that everyone agreed was tastier. But starting in the early 1900s, banana plantations were invaded by a fungus called Panama disease and vanished one by one. Forest would be cleared for new banana fields, and healthy fruit would grow there for a while, but eventually succumb.

By 1960, the Gros Michel was essentially extinct and the banana industry nearly bankrupt. It was saved at the last minute by the Cavendish, a Chinese variety that had been considered something close to junk: inferior in taste, easy to bruise (and therefore hard to ship) and too small to appeal to consumers. But it did resist the blight.

Over the past decade, however, a new, more virulent strain of Panama disease has begun to spread across the world, and this time the Cavendish is not immune. The fungus is expected to reach Latin America in 5 to 10 years, maybe 20. The big banana companies have been slow to finance efforts to find either a cure for the fungus or a banana that resists it. Nor has enough been done to aid efforts to diversify the world’s banana crop by preserving little-known varieties of the fruit that grow in Africa and Asia.

In recent years, American consumers have begun seeing the benefits — to health, to the economy and to the environment — of buying foods that are grown close to our homes. Getting used to life without bananas will take some adjustment. What other fruit can you slice onto your breakfast cereal?

But bananas have always been an emblem of a long-distance food chain. Perhaps it’s time we recognize bananas for what they are: an exotic fruit that, some day soon, may slip beyond our reach.

Dan Koeppel is the author of “Banana: The Fate of the Fruit That Changed the World.”

HARARE, Zimbabwe - Opposition leader Morgan Tsvangirai said Sunday he is pulling out of this week's presidential runoff because of mounting violence and intimidation against his supporters.

Tsvangirai announced his decision during a news conference in Zimbabwe's capital after thousands of ruling party militants blockaded the site of the opposition's main campaign rally.

"Conditions as of today do not permit the holding of a credible poll," Tsvangirai said. "Given the totality of these circumstances, we believe a credible election is impossible. We can't ask the people to cast their vote on June 27 when that vote will cost their lives. We will no longer participate in this violent sham of an election."

Tsvangirai said he would put forward new proposals by Wednesday on how take the country forward. He did not provide any details about what the proposals would include.

"Our victory is certain, but it can only be delayed," he said.

Tsvangirai had hoped to address his main campaign rally ahead of the runoff against 84-year-old President Robert Mugabe, who has held power since independence from Britain in 1980.

But the Movement for Democratic Change claimed the militants were beating opposition supporters who were trying to reach the venue Sunday and said at least two were seriously injured.

It said the militants attacked journalists and forced African election monitors near the rally site to flee. Election monitors could not immediately be reached for comment and there was no independent confirmation of the opposition claims.

Tsvangirai won the March 29 vote but not by an absolute majority. Campaigning for the first round election was generally peaceful, but the runoff has been overshadowed by violence and intimidation, especially in rural areas.

Independent human rights groups say 85 people have died and tens of thousands have been displaced from their homes, most of them opposition supporters.

Tsvangirai's attempts to tour the country have been stymied by police at roadblocks, and the state-controlled media have banned opposition advertisements, claiming they "contain inappropriate language and information." The media cited one ad that claimed that Tsvangirai won the election, "which is not the case, hence the runoff."

Tendai Biti, the opposition party's No. 2, was arrested within minutes of his return from South Africa last week and is being held on treason charges.

"It is evident that the Mugabe regime has disregarded regional and continental opinion that has been calling for an end to disruption of MDC election campaign programs, state sanctioned brutality, violence and harassment of the people of Zimbabwe," the opposition said in a statement.

At a rally in the western city of Bulawayo on Friday, Mugabe said that the opposition was lying about the violence and said everywhere he visited was peaceful. His powerful police chief pinned the blame firmly on the opposition and said that police would clamp down.

Mugabe was lauded early in his rule for campaigning for racial reconciliation. But in recent years, he has been accused of ruining the economy and holding onto power through fraud and intimidation.

The economic slide of what was once the region's breadbasket has been blamed on the collapse of the key agriculture sector after often-violent seizures of farmland from whites.

Mugabe claimed he ordered the seizures, begun in 2002, to benefit poor blacks. But many of the farms instead went to his loyalists.

It does look exceptionally likely that Justice Scalia is writing the principal opinion for the Court in Heller – the D.C. guns case. That is the only opinion remaining from the sitting and he is the only member of the Court not to have written a majority opinion from the sitting. There is no indication that he lost a majority from March. His only dissent from the sitting is for two Justices in Indiana v. Edwards. So, that’s a good sign for advocates of a strong individual rights conception of the Second Amendment and a bad sign for D.C.